It is desirable in a number of applications to be able to identify a person or an item and to thereafter track the person or item. For example, a number of military, intelligence and/or law enforcement agencies may desire to identify and track individuals or items for security purposes or to otherwise gather information about the individuals or items as well as the route or path of travel of the individuals or items.
In one common example, an individual can be identified and, to some degree, tracked by identifying the individual at each of a plurality of security checkpoints, such as those located in airports, along borders and the like. At such security checkpoints, an individual is generally required to provide a means of identification, such as a driver's license, a passport or the like. Similarly, items may be identified and tracked by gathering information about the items being shipped into or out of a country during a border inspection or the like. As will be apparent, however, the tracking afforded by such techniques is relatively limited and consists merely of the identification of the individual at one or more discrete locations with little or no information provided regarding the travel of the individual between those discrete inspection stations. Additionally, such conventional techniques for identifying an individual require the participation of the individual and, as such, are not generally performed surreptitiously, as would be desired in some instances, such as in some military, intelligence and such or law enforcement contexts.
One alternative technique for identifying and tracking an individual or an item has been proposed in which tags may be mechanically affixed to an item including, for example, an item carried by or otherwise associated with an individual. For example, a vehicle driven by an individual may be tagged. In accordance with this technique, the tags that are mechanically affixed to an item may be optically interrogated in order to locate and track the item. Since the tags must be physically attached to the item, the tags are generally unable to locate and track an individual in as robust a manner as desired with the technique being unable to locate and track the individual in those instances in which an individual does not carry an item that has been tagged or is not riding in a vehicle that has been tagged. Additionally, it may be difficult, if not impossible, to mechanically affix the tags to the item in a surreptitious manner as would be desired in some instances, such as in the context of military, intelligence and/or law enforcement activities.
Accordingly, it would be desirable to provide an improved method and apparatus for identifying, locating and tracking individuals or items without alerting or otherwise imposing upon the individual.